题解 | #【模板】静态区间和（前缀和）#

#include <stdio.h>
#include <stdlib.h>
int main() {
    int n, q;
    if (scanf("%d %d", &n, &q) != EOF) {
        int* arr = (int*)malloc(sizeof(int) * n);
        for(int i = 0; i < n; i++) {
            scanf("%d", &arr[i]);
        }
        int l, r;
        long long* sum = (long long*)malloc(sizeof(long long) * (n + 1));
        sum[-1] = 0;
        for(int i = 0; i < n; i++) {
            sum[i] = arr[i] + sum[i - 1];
        }
        for(int i = 0; i < q; i++) {
            scanf("%d %d", &l, &r);
            
            
            printf("%lld\n", sum[r - 1] - sum[l - 2]);
        }
        free(arr);
    } else {
        printf("no input");
    }
    return 0;
}